https://www.gamespot.com/articles/fortnite-wont-add-avengers-skins-as-part-of-thanos/1100-6458768/

In surprising news, Fortnite: Battle Royale has introduced a limited-time mode themed around Avengers: Infinity War. The crossover event will give players the opportunity to actually play as Thanos, but if you're expecting what would appear to be the obvious complement to this--Avengers skins--you'd unfortunately be wrong.